Seal for rotary hydraulic machine



March 23, 1965 R. s. SPROULE 3,174,720

SEAL FOR ROTARY HYDRAULIC MACHINE Filed June 10, 1963 7 Sheets-Sheet l AH? SUPPLY INVENTOR. ROBERT S. SPEOULE 5 RIVEK March 23, 1965 R. s. SPROULE 3,174,720

SEAL FOR ROTARY HYDRAULIC MACHINE Filed June 10, 1963 7 Sheets-Sheet 2 INVENTOR.

ROBE ET 5 SPROULE March 1965 R. s. SPROULE 3,174,

AL 0R RO'" 1 HYDRAULIC MACHINE Filed June 10, 1963 7 Sheets-Sheet 3 IN ENTOR. ROBERT 5. 5 OULE BY E A; TOENEK March 23, 1965 R. s. SPROULE 3,174,720

SEAL FOR ROTARY HYDRAULIC MACHINE Filed June 10, 1963 7 Sheets-Sheet 4 ROBERT S. SPEOLJLE AT OPNEM/ March 23, 1965 s, sP ouL 3,174,720

SEAL FOR ROTARY HYDRAULIC MACHINE Filed June 10, 1963 7 Sheets-Sheet 5 III/4 INVENTOR. EOBE'ET 5. SPEOULE:

ATTORNEY March 23, 1965 R. s. SPROULE 3,174,720

SEAL FOR ROTARY HYDRAULIC MACHINE Filed June 10, 1965 7 Sheets-Sheet 6 INVENTOR. ROBERT S. SPEOLJLE ATTORNEY March 23, 1965 R. s. SPROULE 3,174,720

7 Sheets-Sheet '7 I I ale INVENTOR. 'EOBEET 5. SPEOLJLE.

g d TTOPNEL United States Patent 3,174,720 SEAL FOR ROTAR HYDRAULIC MACHINE Robert S. Sproule, Montreal, Quebec, Canada, assignor to Dominion Engineering Works, Limited Filed June 10, 1963, Ser. No. 286,646 3 Claims. (Cl. 253-26) In a mixed flow pump, Francis turbine, or other hydraulic turbomachine having a shrouded rotor, means are sometimes provided for maintaining the spaces between the outsides of the shrouds and the adjacent static structure filled with air.

In machines of this type, there is a tendency for the air to escape past the rotor seals which are provided to prevent excessive leakage of the working fluid past the rotor from the high to the low pressure side.

I have invented means to prevent such leakage or" air past these seals.

Conventional cylindrical, small-clearance seals have not proved etfective in retaining the air.

It is an object of the present invention to provide a new and improved seal for hydraulic turbomachines whereby the escape of air is prevented.

Another object of the invention is to provide a new and improved seal which, though not requiring impractically small running clearances, prevents escape of air.

Another object of the invention is to provide a new and improved seal which utilizes centrifugal separation of air and the working fluid to prevent escape of the air.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings. It will be understood that changes may be made in the details of construction; the arrangement shown and described is the preferred form of invention and has been given by way of illustration only.

Referring to the drawings:

FIG. 1 is a vertical diametral sectional view of a Francis turbine or pump-turbine.

FIG. 2 is a fragmentary sectional view of the circled portion of FIG. 1, showing the preferred execution of the invention.

FIG. 3 is a fragmentary sectional view of the circled portion of FIG. 1 showing an alternative execution of the invention in which upward movement of the rotor is less restricted than in the execution according to FIG. 2.

FIG. 4 is a fragmentary sectional view of the circled portion of FIG. 1 showing an alternative execution of the invention in which a beveled construction is employed in the upper part of the seal assembly in place of the stepped construction shown in FIGS. 2 and 3.

FIG. 5 is a fragmentary sectional view of the circled portion of FIG. 1 showing an alternative execution of the invention in which a combination of beveled and stepped construction is employed.

FIG. 6 is a fragmentary sectional view of the circled portion of FIG. 1 showing an alternative execution of the invention in which a fully beveled construction of the sealing surfaces is employed; and

FIG. 7 is a fragmentary sectional view of the circled portion of FIG. 1 showing an alternative execution of the invention in which the beveled construction of FIG. 4 is employed in a construction which eliminates a separate rotor seal member.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout, and with particular reference to FIG. 1, when the machine operates as a turbine, water from inlet casing It) is directed by stay vanes 11 and wicket gates 12 to the runner shown generally at 13, and is discharged by way of base ring 32 and draft tube 33. Runner 13 "ice is attached to shaft 15. Shaft 15 is journalled in guide bearing 14. It will be understood that when this machine operates as a pump, runner 13 and shaft 15 are rotated by external power applied to shaft 15, and the water flow is in the reverse direction.

It has been found desirable in machines of this type, to introduce a fluid of low density and viscosity, usually air, by means of a pipe, into space 16 between runner 13 and headcover 17, also into space 18 between runner 13 and lower cover 19. Due to rotation imparted by runner 13, the air is centrifuged towards the axis of rotation and, therefore, towards the seals, past which, with conventional executions, the air escapes.

FIG. 2 illustrates in detail the seal and adjacent portions of runner 13, lower cover 19 and base ring 32.

With reference to FIG. 2, the runner, shown generally at 13, is provided with rotary seal ring 20 mounted on the lower part of runner band 29, and is located within bore 21 of lower cover 19. Annular space 23 is the radial clearance between the periphery of seal ring 20 and bore 21.

Annular space 22, of lesser diameter than annular space 23, is the radial clearance between bore 27 of static seal ring 34 and the periphery 28 of runner band 29.

A further annular space 25, bounded by horizontal face 39 of static seal ring 34 and horizontal face 31 of rotary seal ring 20 connects annular spaces 22 and 23-. The cross-section of annular space 25 is characterized by the axial dimension being smaller than the radial dimension.

Annular groove 26 is formed in bore 21 of lower cover 19 intermediate of its upper and lower extremities. Ducts 24 supply water to groove 26 at a pressure greater than the pressure in space 18.

Since the cross-section of annular space 25 has a significant radial dimension and since rotation is imparted, by rotary seal ring 20, to any fluid or fluids contained therein, centrifugal separation of fluids of different densities, such as air and water, is effected, whereby a standing water seal is set up in the outer region of space 25 which prevents escape of the air from space 18.

Although the invention has been described as applied to the sealing of air in the band space of the Francis machine, it will be understood that the same seal may be applied to seal air in the crown space of said Francis machine. It will be further understood that the seal provided by the present invention has been described with relation to a Francis-type hydraulic machine for purposes of illustration only, and that many variations, such as those shown in FIGS. 3, 4, 5, 6 and 7, may be employed without departure from the spirit or scope of the invention.

In FIG. 3, the length of the rotary seal ring Zila has been shortened (see face 31a) to provide a larger annular space 25a than the corresponding space 25 in FIG. 2, thereby allowing for greater upward movement of the rotor.

In FIG. 4, the bore 27b of static seal ring 34b is shown bevelled so as to provide an annular space 25b between horizontal face 31b of the rotary seal ring 25b and bore 27b, extending at an angle to the axis of rotation.

In FIG. 5, the lower cover 19c is provided with a bevelled bore 270 and a stepped horizontal face 30c. The bevelled bore 270 is shown substantially parallel to the periphery 280 of the runner band 29 and the stepped face 300 is substantially parallel to the horizontal face 310 of the runner band, thereby providing annular spaces 23c and 250.

In FIG. 6, a fully bevelled bore 27d is shown opposite to the periphery 28d of the runner band 29 thereby providing an annular space 25d between the band and the static seal ring 340'.

In FIG. 7, the rotor seal ring is omitted and a projection 35 on the periphery 28e of the runner band 29 is substituted therefor. Annular space 25e is provided between the projection 35 and the bore 27e of static seal ring 34e.

The operation of the device is believed to be apparent from the foregoing description, and it will be apparent that I have provided new and improved means for accomplishing all of the objects and advantages of the machine.

I claim:

1. In a rotary hydraulic machine comprising a stationary housing, a rotating member, said member comprising spaced axially upper and lower shrouds having blades secured therebetween, and defining a fluid flow channel, said lower shroud having a high pressure edge at a large diameter than the low pressure edge, said sta tionary housing having a portion surrounding said high pressure edge of said lower. shroud to cooperate therewith to provide a close running clearance therebetween, said stationary housing having a second portion extending from said first portion toward said low pressure edge of said lower shroud and spaced therefrom to define an an nular space between said lower shroud and the stationary housing, sealing means between the lower shroud adjacent its low pressure edge and the second portion of the stat-ionary structure extending toward the low pressure edge, said sealing means between said lower'shroud and the second portion of said stationary structure comprising a pair of seal elements, one of said pair of seal elements being replaceable and carried by the second portion of the stationary structure adjacent the annular space and cooperating with said stationary structure to define one side of an annular recess in said second portion of said sta-' tionary structure, the second of said seal elements defining the low pressure edge of said lower shroud and having an annular outward projection thereon extending into said annular recess and overlapping said first seal element, means for injecting high pressure air into the annular space between the lower shroud and the second portion of the stationary housing, and means to inject a high pressure liquid lubricant into said annular recess to prevent escape of air past the low pressure edge of said lower shroud into said fluid flow channel.

2. A rotary hydraulic machine as claimed in claim 1 in which said means to inject a high pressure liquid lubricant into said annular recess comprises an annular groove in the stationary structure communicating with said annular recess, and supplied with liquid lubricant by means of a plurality of ducts extending through the stationary structure into said annular groove.

3. A rotary hydraulic machine as claimed in claim 1 in which said means to inject a high pressure liquid lubricant into said annular recess comprises an annular groove in the stationary structure communicating with said annular recess, and duct means to supply liquid lubricant to the annular groove to maintain the pressure in the annular recess higher than the pressure in said annular space.

References Cited by the Examiner UNITED STATES PATENTS KARL J. ALBRECHT, Primary Examiner. JOSEPH H. BRANSON, 1a., Examiner. 

1. IN A ROTARY HYDRAULIC MACHINE COMPRISING A STATIONARY HOUSING, A ROTATING MEMBER, SAID MEMBER COMPRISING SPACED AXIALLY UPPER AND LOWER SHROUDS HAVING BLADES SECURED THEREBETWEEN, AND DEFINING A FLUID FLOW CHANNEL, SAID LOWER SHROUD HAVING A HIGH PRESSURE EDGE AT A LARGE DIAMETER THAN THE LOW PRESSURE EDGE, SAID STATIONARY HOUSING HAVING A PORTION SURROUNDING SAID HIGH PRESSURE EDGE OF SAID LOWER SHROUD TO COOPERATE THEREWITH TO PROVIDE A CLOSE RUNNING CLEARANCE THEREBETWEEN, SAID STATIONARY HOUSING HAVING A SECOND PORTION EXTENDING FROM SAID FIRST PORTION TOWARD SAID LOW PRESSURE EDGE OF SAID LOWER SHROUD AND SPACED THEREFROM TO DEFINE AN ANNULAR SPACE BETWEEN SAID LOWER SHROUD AND THE STATIONARY HOUSING, SEALING MEANS BETWEEN THE LOWER SHROUD ADJACENT ITS LOW PRESSURE EDGE AND THE SECOND PORTION OF THE STATIONARY STRUCTURE EXTENDING TOWARD THE LOW PRESSURE EDGE, SAID SEALING MEANS BETWEEN SAID LOWER SHROUD AND THE SECOND PORTION OF SAID STATIONARY STRUCTURE COMPRISING A PAIR OF SEAL ELEMENTS, ONE OF SAID PAIR OF SEAL ELEMENTS BEING REPLACEABLE AND CARRIED BY THE ANNULAR SPACE AND COSTATIONARY STRUCTURE ADJACENT THE ANNULAR SPACE AND COOPERATING WITH SAID STATIONARY STRUCTURE TO DEFINE ONE SIDE OF AN ANNULAR RECESS IN SAID SECOND PORTION OF SAID STATIONARY STRUCTURE, THE SECOND OF SAID SEAL ELEMENTS DEFINING THE LOW PRESSUE EDGE OF SAID LOWER SHROUD AND HAVING AN ANNULAR OUTWARD PROJECTION THEREON EXTENDING INTO SAID ANNULAR RECESS AND OVERLAPPING SAID FIRST SEAL ELEMENT, MEANS FOR INJECTING HIGH PRESSURE AIR INTO THE ANNULAR SPACE BETWEEN THE LOWER SHROUD AND THE SECOND PORTION OF THE STATIONARY HOUSING, AND MEANS TO INJECT A HIGH PRESSURE LIQUID LUBRICANT INTO SAID ANNULAR RECESS TO PREVENT ESCAPE OF AIR PAST THE LOW PRESSURE EDGE OF SAID LOWER SHROUD INTO SAID FLUID FLOW CHANNEL. 